As his pro rata share of the expense of administration of the order, each handler (except a handler pursuant to § 1049.9(b) or (c) for milk delivered to pool plants) shall pay to the market administrator on or before the 15th day after the end of the month 4 cents per hundredweight, or such lesser amount as the Secretary may prescribe, with respect to:

(a) Producer milk (including such handler's own farm production) and milk received from handler pursuant to § 1049.9(b) or (c);

(b) Receipts of concentrated fluid milk products from unregulated supply plants and receipts of nonfluid milk products assigned to Class I use pursuant to § 1049.43(d) and other source milk allocated to Class I pursuant to § 1049.44 (a)(7) and (a)(11) and the corresponding steps of § 1049.44(b), except such other source milk that is excluded from the computations pursuant to § 1049.60 (d) and (f); and

(c) Route disposition in the marketing area from a partially regulated distributing plant that exceeds the skim milk and butterfat subtracted pursuant to § 1049.76(a)(2).